Is this the solution to our pollution?1:06

A look into the recent accidental discovery of an enzyme that could be the solution to the world's pollution problem.

April 17th 2018

8 months ago

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A small sea horse grabs on to garbage in Indonesia. This tiny sea horse drifted through our snorkelling site along with a raft of tide-driven trash, especially bits of plastic. Picture: Justin HofmanSource:News Corp Australia

SCIENTISTS have accidentally created a mutant enzyme which could help address a major global pollution problem.

Researchers in the US and the UK say they inadvertently engineered the mutant enzyme after examining a particular bacterium discovered in Japan a few years ago.

Japanese researchers believe the bacterium evolved fairly recently in a waste recycling centre, since plastics were not invented until the 1940s, meaning the bacteria has evolved relatively recently to eat the vast sum of plastic we produce.

Known as Ideonella sakaiensis, it appears to feed exclusively on a type of plastic known as polyethylene terephthalate (PET), used widely in plastic bottles.

Despite recycling efforts, most plastic can persist for hundreds of years in the environment, so researchers are searching for better ways to eliminate it — and they think they’ve stumbled on a potential answer.

The researchers’ goal was to understand how one of the bacteria’s enzymes — called PETase — worked, by figuring out its structure.

“But they ended up going a step further and accidentally engineered an enzyme which was even better at breaking down PET plastics,” said a report of their discovery.

Scientists at the University of Portsmouth in the UK and the US Energy Department’s National Renewable Energy Laboratory published their findings this week in the Proceedings of the National Academy of Sciences, a peer-reviewed US journal.

British man Richard Horner filmed this video while diving off the coast of Nusa Penida, a small island not far from the popular tourist destination of Bali. Screen grabs from YouTubeSource:YouTube

Using a super-powerful X-ray, 10 billion times brighter than the Sun, they were able to make an ultra-high-resolution three-dimensional model of the enzyme. From there they were able to use computer modelling and found it looked similar to another enzyme, cutinase, found in fungus and bacteria.

One area of the PETase was a bit different, though, and researchers hypothesised that this was the part that allowed it to degrade man-made plastic.

So they mutated the PETase active site to make it more like cutinase, and unexpectedly found that this mutant enzyme was even better than the natural PETase at breaking down PET.

Researchers say they are now working on further improvements to the enzyme, with the hope of eventually scaling it up for industrial use in breaking down plastics.

“Serendipity often plays a significant role in fundamental scientific research, and our discovery here is no exception,” said study author John McGeehan, professor in the School of Biological Sciences at Portsmouth.

“Although the improvement is modest, this unanticipated discovery suggests that there is room to further improve these enzymes, moving us closer to a recycling solution for the ever-growing mountain of discarded plastics.”

“The presence of plastic in the ocean and oceans is one of the greatest threats to the conservation of wildlife throughout the world, as many animals are trapped in the trash or ingest large quantities of plastics that end up causing their death,” local wildlife authorities said in a statement regarding the discovery.

— With AFP

A 10-metre installation depicting a whale made up of 250kg of plastic waste, in Rome, on April 16, 2018. The 250kg of plastic used to create "Plasticus" is the same amount of plastic that goes into the ocean every second. Picture: Andreas SolaroSource:AFP